MATH Instructions Questions

[jaywillnot]

Hey Lancie,
I opened the links you posted, and tried the program out. Apparently, I plugged a wrong B3 data file in somewhere and I'm only executing the S:4 bit it seems. Some of the MOV and SQL and SQO instructions have been cut slightly off so that I can't tell exactly what the B3 words are, for exaple: B3:0 or B3:/0. Maybe that's where I messed up. What is your synopsis?
Thank you,
Jay

 

[Doug-P]

Syntax is important

I can't tell exactly what the B3 words are, for exaple: B3:0 or B3:/0.

You need to establish a baseline reference for discussing what you're doing in ladder. Part of this is correctly describing what you are seeing/trying to do.

In your post quoted above B3:0 is a valid address. B3:/0 is not. Although you might enter B3:/0 from the keyboard, RSLogix will insert the implied word number of zero and convert it to B3:0/0 when it builds the rung. In fact, you can enter a semicolon and it will convert that to a colon when the rung is built.

You can get a better understanding of these concepts by checking out appendix D (Programming instruction references), and E (Data file organization and addressing) of the SLC-500 instruction set reference.

http://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1747-rm001_-en-p.pdf

 

[Lancie1]

Hey Lancie,
I opened the links you posted, and tried the program out. Apparently, I plugged a wrong B3 data file in somewhere and I'm only executing the S:4 bit it seems.

In my Post #8, the 8-rung "Sequenced Light Array R4.zip" file contains the LogixPro RSL program. If you download that, un-ZIP and run it with LogixPro, you will not have to wonder about B3:0. The only place B3:0 appears is in Rungs 3 and 5, and both are for the word "B3:0", nothing else.

Remember, this program starts out by generating and loading the 98 pseudo-random numbers into the Sequencer, so it requires 98 x 0.1 = 9.8 seconds before you see any flashing lights. Be patient!

Oh, you do have to set up an On/Off maintained-contact switch for Input I:1/0, and then switch to RUN mode and turn ON that switch. I think that you know how to do that.

 

[jaywillnot]

Ahhhh, ok....
Obviously I missed that part of the link. My dang ADD must have been in overdrive that night Lancie. Thank you for your help sir.

 

[jaywillnot]

In your post quoted above B3:0 is a valid address. B3:/0 is not. Although you might enter B3:/0 from the keyboard, RSLogix will insert the implied word number of zero and convert it to B3:0/0 when it builds the rung.

Doug, I apologize. I must have fat fingered the keyboard when I wrote the reply. It wasn't my intention to cause confusion. Thank you for your help sir.
It completely amazes me how total strangers on this forum are willing to help those in need. You guys are awesome!!

 

[jaywillnot]

Hey Lancie,
I added the maintained-contact on/off switch and the program ran flawlessly. Thank you again for your help.
Jay

 

[Lancie1]

I added the maintained-contact on/off switch and the program ran flawlessly.

I have noticed an alarming trend in student programs - very few now bother to put in such boring details as Start and Stop buttons in their PLC logic. There are very few real-world machines that do not need some method to Start and Stop the equipment. The very first instruction to put into your student programs should always be a STOP pushbutton or switch. There are exceptions, such as the old traffic light program.